Kaons and antikaons in hot and dense hadronic matter

The medium modification of kaon and antikaon masses, compatible with low energy KN scattering data, are studied in a chiral SU(3) model. The mutual interactions with baryons in hot hadronic matter and the effects from the baryonic Dirac sea on the K(${\rm {\bar K}}$) masses are examined. The in-medium masses from the chiral SU(3) effective model are compared to those from chiral perturbation theory. Furthermore, the influence of these in-medium effects on kaon rapidity distributions and transverse energy spectra as well as the $K, \bar{K}$ flow pattern in heavy-ion collision experiments at 1.5 to 2 A$\cdot$GeV are investigated within the HSD transport approach. Detailed predictions on the transverse momentum and rapidity dependence of directed flow $v_1$ and the elliptic flow $v_2$ are provided for Ni+Ni at 1.93 A$\cdot$GeV within the various models, that can be used to determine the in-medium $K^\pm$ properties from the experimental side in the near future.